/*=========================================================================
 *
 *  Copyright Insight Software Consortium
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/

#include "itkConnectedComponentImageFilter.h"
#include "itkImageRegionConstIteratorWithIndex.h"
#include "itkSimpleFilterWatcher.h"
#include "itkTestingMacros.h"

int itkConnectedComponentImageFilterBackgroundTest( int argc, char* argv[] )
{

  if ( argc < 2 )
    {
    std::cout << "Usage: " << itkNameOfTestExecutableMacro(argv) << " <background value>\n";
    return EXIT_FAILURE;
    }

  using PixelType = int;
  constexpr unsigned int Dimension = 2;
  using ImageType = itk::Image< PixelType, Dimension >;

  auto background = static_cast< PixelType >( std::stoi( argv[ 1 ] ) );

  // Create an image with an arbitrary background value and a number
  // of islands with pixel values above and below the background value
  ImageType::Pointer image = ImageType::New();
  ImageType::SizeType size;
  size.Fill( 512 );
  image->SetRegions( size );
  image->Allocate();
  image->FillBuffer( 0 );

  // Set up islands
  ImageType::IndexType index1;
  index1[0] = 10;
  index1[1] = 11;
  image->SetPixel( index1, 1 );

  ImageType::IndexType index2;
  index2[0] = 100;
  index2[1] = 101;
  image->SetPixel( index2, 2 );

  // Instantiate and run the filter
  using FilterType = itk::ConnectedComponentImageFilter< ImageType, ImageType >;
  FilterType::Pointer filter = FilterType::New();
  filter->SetBackgroundValue( background );
  filter->SetInput( image );
  itk::SimpleFilterWatcher watcher( filter );

  try
    {
    filter->Update();
     }
  catch( itk::ExceptionObject & excep )
    {
    std::cerr << "exception caught:" << std::endl;
    std::cerr << excep << std::endl;
    return EXIT_FAILURE;
    }

  if ( filter->GetObjectCount() != 2 )
    {
    std::cerr << "Expected 2 objects, got " << filter->GetObjectCount() << " instead.\n";
    }

  ImageType * output = filter->GetOutput();

  using IteratorType = itk::ImageRegionConstIteratorWithIndex< ImageType >;
  IteratorType iterator( output, output->GetLargestPossibleRegion() );
  while ( !iterator.IsAtEnd() )
    {
    PixelType value = iterator.Get();
    ImageType::IndexType index = iterator.GetIndex();
    if ( index == index1 || index == index2 )
      {
      // Check that objects don't have the background value
      if ( value == background )
        {
        std::cerr << "Pixel at index " << index << " has background value "
                  << "but should have an object label instead.\n";
        return EXIT_FAILURE;
        }
      }
    else
      {
      if ( value != background )
        {
        std::cerr << "Pixel at index " << index << " has value " << value
                  << " but should have bacground value: " << background << "\n";
        return EXIT_FAILURE;
        }
      }
    ++iterator;
    }

  return EXIT_SUCCESS;
}
